1. Field of the Invention
The present invention relates generally to over-center draw latches for use in securing together two closure members and more particularly to overcenter draw latches of the flexible or elastic type.
2. Brief Description of the Prior Art
Many types of over-center draw latches are known. Such latches essentially comprise a keeper, a mounting bracket, a lever and a catch, with the catch being adapted to engage the keeper in the secured position of the latch. Typically, such latches are of a molded plastic or metal construction or, in some instances, a combination of both plastic and metal. These varieties of latches often are considered desirable because they provide positive over-center latching in relation to the closure members to which they are attached. A disadvantage in these latches, however, is the fact that considerable precision is required in the location and alignment of the closure members and in the installation of the latch in order to ensure proper latching operation. Specifically, on installation, the bracket and keeper members are required to be positioned aligned to one another so as to allow engagement between the catch and keeper during latching. In a similar regard, another disadvantage is that such latches are incapable of operating in applications where it is required that one closure member move relative to the other, such as where relative vibration of the closure members will occur.
Flexible draw latches are another type of over-center draw latch known in the art and have been used for many years. Essentially, a flexible draw latch includes a base, a latch body comprising a rubber stretch arm or other suitable flexible material affixed to the base, a lever and a keeper. Some examples of flexible draw latches are shown in U.S. Pat. No. 4,830,413, issued May 16, 1989; U.S. Pat. No. 4,828,298, issued May 9, 1989 and U.S. Pat. No. 4,804,215, issued Feb. 14, 1989, which are all assigned to Southco, Inc., the assignee of the present application. The complete disclosures of these patents are incorporated herein by reference. Typically, flexible draw latches are used to secure loose fitting hoods or covers on heavy machinery or mechanical equipment. In operation, the rubber stretch arm is pulled up and into engagement with the keeper through rotation of the lever, with the elasticity of the rubber arm operating to keep the hood or cover secure. Generally, these types of latches are considered desirable because the flexibility of the rubber arm will compensate for misalignment of the bracket and keeper which may result in the location and alignment of the closure members and during installation. Furthermore, the flexibility of these latches also permit the closure members to move relative to one another without causing the latch to release or otherwise become inoperative, thus being desirable for use in situations where vibrations of the closure members relative to one another do occur. Another advantage of these flexible draw latches is that the load capability of the latch can be varied, within a range, by simply increasing or decreasing the distance between the bracket and the keeper and, thus, the tension on the rubber stretch arm. Despite these foregoing advantages, there are certain drawbacks to the operation of prior art flexible draw latches. One known problem is in the manner in which the components of the flexible draw latches are connected. For instance, the entire load which is produced as the latch body is stretched during operation is transmitted through to the base and lever and can over stress the connection of these members. Furthermore, another problem observed due to the characteristics of the latch body occurs at the point of connection with the base and lever. In particular, where the latch body is connected to the base and lever by a pivot pin, the most common type of failure that has been found to occur results in a split forming in the latch body which allows it to detach from the base or lever. Specifically, in latches of this type, the pivot pins are secured through holes passing through the latch body which in turn are connected with the base and lever, and a split forming proximate any one of the holes in the latch body allows the latch to come apart at that point. In addition, another similar problem is that the pivot pins are often times not securely retained within the latch structure and also require additional tools or equipment to install.
Because of these and other shortcomings associated with flexible draw latches presently employed, there now exists a need for an improved flexible draw latch which overcome the deficiencies of the prior art.